HKDSE Geography/M1/Continental-Continental Destructive Plate Boundaries
When two continental crusts collide, neither crust is subducted as they are of roughly equal density. This collision is found along the Alpine-Himalayan Belt, where the Indo-Australian, Arabian and African plates collide with the Eurasian Plate.
The World's Destructive Plate Boundaries[edit | edit source]
|Circum-Pacific Belt||Pacific||North American||
The Himalayas (Indo-Australian + Eurasian)[edit | edit source]
Note: This chapter involves a lot of processes. All of them must be memorised. For longer sentences, the important keywords will be underlined to facilitate memory.
- Converging/sinking magma currents between the Indo-Australian and Eurasian plates cause the two plates to converge with each other under compressional force, forming a destructive plate boundary
- Denser, thinner, basaltic oceanic crust from the Indo-Australian Plate is subducted under lighter, thicker continental crust from the Eurasian Plate
- Sediments are washed ashore on the Eurasian plate
- As the plates converge, water is squeezed out and the sediments are compacted to form sedimentary rock
- The continental crust of the Indo-Australian and Eurasian plates are equally light and neither can subduct under the other
- The sedimentary rocks are compressed to form a fold mountain range, the Himalayas.
Various HKCEE MC questions throughout the years have confirmed that the Himalayas sometimes experience earthquakes, but rarely experience volcanic eruptions.